Process of weighting fibers and the product thereof



Patented Feb. 5, 1935 PROCESS OF WEEGHTING FIBERS AND PRODUCT THEREOFTHE Olav Berg, Paterson, Max Imhoff, Clifton, and Oernulf E. Heiberg,Hawthorne, N. 3.; said Heiberg assignor to said Berg and Irnhoif; AlbertCatalane and William W. Evans executors of said Olav Berg, deceased NoDrawing. Application August 24, 1926,

Serial No. 131,310

16 Claims.

This invention relates to the chemical treatment of fibers, especiallythose of silk, for the purpose of increasing their size and weight, andto the product of such treatment. Our process relates more particularlyto the treatment of tin weighted silk and its object is to provide newand useful steps to be taken after a preliminary tin weightingtreatment, which have many advantages both as to the method employed andas to the resultant article, over such as have been known heretofore.

It is customary in the art to treat silk fibers with a solution of tintetrachloride and to follow this treatment with one in sodium phosphate.These treatments are usually repeated until the desired weight isobtained. But these treatments are expensive and no great amount of suchloading is possible without injuring the elasticity and strength of thefibers, making them tender and brittle and subject to deterioration withage.

The important feature of our invention is that after the silk is given apreliminary treatment with some other weight giving compounds, we applya treatment with zinc or cadmium compounds,or both zinc and cadmiumcompounds. The preliminary treatment may be any one of the known methodsof tin weighting. We have found that practically any soluble zinc orcadmium compound can be used, but not all with the same advantage. Theresult is greatly dependent upon the nature of the solution.

If silk fiber has been preliminarily treated with tin tetrachloride andsodium phosphate, a treatment in zinc or cadmium sulphate or nitrate 0will not add materially to the weight and volume of the fiber. This isprobably due to the fact that when a small amount of zinc oxide orcadmium oxide has been taken up by the fiber, sulphuric or nitrate acidwill have been liberated and will prevent any more oxide from beingtaken up. We therefore prefer to use a zinc or cadmium salt of a weakacid, for instance, zinc or cadmium, acetate or formate.

A zinc or cadmium salt of a strong acid, for instance, zinc sulphate,can be used with the same advantage as a zinc or cadmium salt of a weakacid, for instance, zinc acetate, if it is used in a buffer solution,that is, in a solution of such a nature that a small addition of acid oralkali will only make a small relative change in the hydrogen-ionconcentration. A solution of sodiurn acetate is suitable for thispurpose.

For certain purposes it is of great advantage to use the zinc or cadmiumin an alkaline solution. Such a solution can be prepared by dissolvingzinc or cadmium oxide in a solution of caustic alkali. It may also beprepared by mixing a solution of a zinc or cadmium salt with ammonia,ammonia being used in sufiicient excess to produce a clear solution.Sometimes we prefer to use the zinc or cadmium salts in an alkalinesolution which contains salts of other metals" or positive groups. Wesometimes use ammonium salts for this purpose.

The process may terminate after the treatment in the solution of thezinc or cadmium compound, but usually we prefer to follow that step witha treatment in a fixing bath. For this purpose we can use a largevariety of different chemicals, for instance, soluble phosphates,soluble silicates, or soluble ferrocyanides. We can also use a number ofcombinations of these and other substances. For instance, as a fixingtreatment we can use a bath of sodium phosphate, follow that with a bathof sodium silicate and finally give a treatment in a fatty soap.

The application of a fixing bath has the advantage of increasing theWeight and volume of the fiber, and to make the zinc or cadmium or zincand cadmium compounds present on the fiber, more insoluble. In somecases it also improves the lustre and scroop of the fiber. The'fixingbath usually imparts to the fiber the property of taking up more zincoxide or cadmium oxide if it is again submerged in a solution of a zinccompound or a cadmium compound. By thus-alternately applying to thefiber a zinc or cadmium compound and a fixing bath, any desired increasein weight can be obtained.

If '75 pounds of boiled oil or degummed silk is treated in a bath of tintetrachloride of a Baum strength of 20 at a temperature of Fahrenheitfor one hour, washed and treated in a slightly alkaline 5 Baum solutionof sodium phosphate at 170 Fahrenheit for one hour and then washed, itsweight will be increased to 86 pounds. Repeating these steps willincrease its weight to 102 pounds. These steps are old and well known.We now put the treated goods into a 3 Baum bath of zinc acetate at 140Fahrenheit for one hour and then wash. After this the weight of thegoods is 108 pounds. A sodium phosphate treatment of 6 Baum strength and140,Fahrenheit for one hour will increase the weight to pounds. Arepetition of the zinc acetate and sodium phosphate baths increases theweight to 139 pounds. Another repetition of the zinc acetate and sodiumphosphate baths increases the weight to 169 pounds. These zinc acetateand sodium phosphate treatments may be repeated again and again withfurther additions of volume and weight.

Thus the desired increase may be obtained without the undesirable use ofan excess of tin compounds. By this process the size of the fiber willgreatly increase, which is the principal object of any weightingprocess. The goods are soft and fiufiy and their appearance greatlyimproved. Furthermore, this treatment is less expensive than the formermethod of repeating tin weighting treatments to obtain similar weights.

We find it desirable to use one or more intercalated treatments with asoluble lead salt, such as lead acetate as described in Patent No.1,579,- 628, issued April 6, 1926, as this has the effect of improvingthe fiber in many ways. It not only increases the weight but improvesthe tone of the fiber, increases its elasticity, improves its dyeingproperties and has a preservative effect. This lead treatment may beapplied at any stage after the tin treatment has been applied. We nowprefer to follow the lead treatment with a bath of sodium phosphate. 3

In the aforesaid Patent No. 1,579,628, the ways of using lead acetatehave been described in detail, and the same ways of treating fibers canbe followed by substituting zinc acetate, with many of: the sameadvantages, especially if some soluble lead compound is used in additionto the zinc treatment.

By the methods now in vogue and employed in the past for the weightingof silk, sodium silicate or other soluble silicates are frequently,applied in connection with tin compounds. Silk fibers can be weighted byalternately treatingthe fiber in a solution of tin tetrachloride and asolution of sodium silicate, but it is more customary first to subjectthe fiber to the alternate action of baths of tin tetrachloride and ofsodium phosphate and thereafter to treat it in a solution of sodiumsilicate. Such application of sodium silicate will greatly increase thesize of the fiber. But silk weighted by tin compounds in connection withsodium silicate is very often tender and brittle and will deteriorate ina comparatively 'short time. After silk, for example, has been weightedby alternate treatments in tin tetrachloride and sodium phosphate, itwill take up a certain amount of silicate when immersed in a solution ofsodium silicate, but after one silicate treatment it has practically noability to take up more.

' It is'known also that if the fibers after the silicate treatment aresubjected to a bath of practically any metallic salt, they will take upabout as much silicate as they did the first time, if they are againsubjected to the action of a solution of a silicate. So it is possibleto increase the weight and volume of fibers which have been treated ashereinbefore described by subjecting them to a bath of sodium silicate.

In thiscase asbefore, one or more intercalated treatments with a solublelead compound will improve the character of the fibers. And as beforethe process maybe ended with a silicate treatment. The process may bestopped after any p- The goods so treated aresoft and fluffy. Goodscontaining a considerable amount of tin weighting with silicate appliedby former methods are subject to shrinkage which undesirablecharacteristic is greatly reduced by this new method. This method ismuch cheaper than the ordinary tin weighting and the appearance of thegoods is better.

We have found that the goods may be given a still greater volume withfew treatments, if the zinc or cadmium compound used be in the form ofan alkaline solution. For example: by two treatments in tintetrachloride and two treatments in sodiiun phosphate as previouslydescribed, the weight of 75 pounds degummed silk will be increased to102 pounds. A treatment in sodium silicate 3 Baum, F. for one half hourwill bring the weight up to 116 pounds. These steps are old.

We now put the silk in an alkaline bath of a zinc salt, prepared asfollows: ammonia is added to a bath of zinc acetate thereby forming aprecipitate, but the addition of ammonia is continued until theprecipitate is dissolved. This alkaline bath of zinc salt is used at 3Baum and 140 F. for one hour, after which the goods are washed- Thisadds somewhat to the weight. When the silicate treatment beforedescribed follows, the weight will increase to pounds. Another treatmentin the alkaline bath of zinc brings the weight up to pounds. Anotherbath of sodium silicate gives further increase of weight and volume.

Thus the desired weight and volume can be obtained with fewer steps thanif zinc or cadmium had been used in a neutral solution. As

before it is sometimes desirable to add a lead compound to the goods andthis may be done as already pointed out.

Again the process may be ended after an the fixing baths described.

The order and number of steps taken may be varied after the tintreatment has first been applied. The process may be applied to fibersin the skein or to textiles and they may be brought to any desiredweight or volume. The treated fibers forma new and useful material.

This description is for illustrative purposes only, as we know that thestrengths, temperatures, acidities and times mentioned, as well as theorder and number of steps, and even the chemicals specified, may bevaried without departing from the scope of the invention, and we intendno limitaitons other than those imposed by the appended claims.

It is understood from this disclosure that the water washing steps, orcleaning with weak acid or alkaline solutions, which are not included inthe claims, may be used after each bath specified.

It is our belief that cadmium is, in a patentable sense, the fullequivalent of zinc, and that the use of cadmium or of cadmium compoundsinstead of zinc or zinc compounds as specified in the claims, would comewithin the scope of the claims.

What We claim is:

1. A process of treating tin weighted fibers which comprises treatingsuch fibers in a solution of an organic zinc salt.

2. A process of treating tin weighted fibers which comprises treatingsuch fibers with a zinc salt in a solution of low acidity which ismaintained at a substantially constant pH value.

3. A process of treating tin weighted fibers which comprises treatingsuch fibers in a solution of zinc acetate.

4. A process of treating tin weighted fibers salt in a solution of lowacidity which is maintained at a substantially constant pH value andthen in a bath of sodium phosphate.

6. A process of treating tin weighted fibers which comprises treatingsuch fibers successively in baths of a zinc salt in a solution of lowacidity which is maintained at a. substantially constant pH value and ina solution of sodium phosphate.

7. A process of treating tin weighted fibers which comprises treatingsuch fibers in successive solutions of zinc acetate and of sodiumphosphate.

8. A process of treating tin weighted fibers which comprises treatingsuch fibers successively in baths of a zinc salt in a bufier solutionand in a solution of sodium phosphate.

9. A process of treating tin weighted fibers which comprises treatingsuch fibers in a solution of zinc acetate and in a bath of lead acetate.

10. A process of treating tin weighted fibers which comprises treatingsuch fibers in solutions of zinc acetate, of lead acetate and of sodiumphosphate.

11. A process of treating tin weighted fibers which comprises treatingsuch fibers in successive solutions of zinc acetate and. of sodiumphosphate with an intercalated treatment with a soluble lead compound.

12. The process of treating silk by subjecting it to a bath containingtin, washing the silk, subjecting it to a bath containing sodiumphosphate, Washing the silk and thereafter subjecting it to a bathcontaining zinc acetate, washing the silk and subjecting it to a bathvcontaining sodium phosphate.

13. The process of treating silk by subjecting it to a bath containingstannic chloride and thereafter subjecting it to a bath containing zincacetate.

14. A fabric weighted by the addition of stannic chloride and zincacetate.

15. A process of treating tin weighted fibers which comprises treatingsuch fibers with a zinc salt in a solution of low acidity which ismaintained at a substantially constant pH value, with an intercalatedtreatment with a soluble lead compound.

16. A process of treating tin weighted fibers which comprises treatingsuch fibers with a zinc salt in a solution of low acidity which ismaintained at a substantially constant pH value, and then in a bath ofsodium phosphate and in a bath of a soluble lead compound.

OLAV BERG. MAX IMHOFF. OERNULF E. HEIBERG.

